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Interspecific nematode signals regulate dispersal behavior.

Kaplan F, Alborn HT, von Reuss SH, Ajredini R, Ali JG, Akyazi F, Stelinski LL, Edison AS, Schroeder FC, Teal PE - PLoS ONE (2012)

Bottom Line: Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends.Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

View Article: PubMed Central - PubMed

Affiliation: Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Gainesville, Florida, United States of America. fkaplan@ufl.edu

ABSTRACT

Background: Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.

Methodology/principal findings: Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.

Conclusions/significance: Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

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Related in: MedlinePlus

An ascaroside blend regulates C. elegans dispersal behavior, and the dispersal blend is recognized by other nematodes.(A) Identification of the dispersal blend. Images (∼250 nematodes) are representative of 9, 10, and 11 experiments of control (0.25% E. coli (HB101)), synthetic blend with 0.25% E. coli (HB101) and dauer supernatant, respectively. (B) Quantification using Image J (http://rsbweb.nih.gov/ij/download.html). Control vs synthetic blend student's t-test unpaired (p<0.02). (C) S. feltiae IJs (∼250) response to the dispersal blend; four experiments for each treatment. (D) Response of root-knot J2s (Meloidogyne spp., mixture of M. incognita, M. javanica, and M. floridensis) to the C. elegans dispersal blend. The data represent 19 and 20 experiments from control water and C. elegans dispersal blend, respectively. At 2 h, using a student's t-test, unpaired, p<0.007.
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pone-0038735-g003: An ascaroside blend regulates C. elegans dispersal behavior, and the dispersal blend is recognized by other nematodes.(A) Identification of the dispersal blend. Images (∼250 nematodes) are representative of 9, 10, and 11 experiments of control (0.25% E. coli (HB101)), synthetic blend with 0.25% E. coli (HB101) and dauer supernatant, respectively. (B) Quantification using Image J (http://rsbweb.nih.gov/ij/download.html). Control vs synthetic blend student's t-test unpaired (p<0.02). (C) S. feltiae IJs (∼250) response to the dispersal blend; four experiments for each treatment. (D) Response of root-knot J2s (Meloidogyne spp., mixture of M. incognita, M. javanica, and M. floridensis) to the C. elegans dispersal blend. The data represent 19 and 20 experiments from control water and C. elegans dispersal blend, respectively. At 2 h, using a student's t-test, unpaired, p<0.007.

Mentions: Next we investigated whether this bioassay could also be used to test for dispersal of C. elegans dauer larvae. For this assay, we used a growth medium from a developmentally synchronized C. elegans liquid culture that had produced 60% dauer larvae [19]. Following removal of all nematodes, this dauer inducing medium containing L1 and L2D secretions strongly induced dispersal behavior in the C. elegans dauer. Using LC-MS, the dauer forming medium was analyzed for the known ascarosides (ascr#1, ascr#2, ascr#3, ascr#4, ascr#5, ascr#6, ascr#7, ascr#8, and icas#9) and was found to contain four known ascarosides (ascr#2, ascr#3, ascr#8, and icas#9) [10], [14], [15] (Fig 2 and Fig S1A), all previously shown to individually promote dauer entry in C. elegans[10], [13], [14]. The concentrations of the ascarosides in the dauer forming culture medium were estimated as: ascr#2 (3.68 pmol/µl), ascr#3 (0.165 pmol/µl), ascr#8 (0.25 pmol/µl) and icas#9 (0.005 pmol/µl). A synthetic blend of these ascarosides was then tested for dispersal activity, using the dauer conditioned medium as a positive control. The media was estimated to contain approximately half of the original 0.5% E. coli (HB101) food source, thus 0.25% E. coli was added to the synthetic test samples, as well as to a water control to prevent food searching behavior induced by the absence of food. The number of dispersing nematodes was normalized to the percent of the positive control response. In the presence of just the food (negative control), approximately 35% of the dauer larvae left the release location. However, with the addition of the synthetic ascaroside blend, nearly twice as many nematodes (62%) moved away from the release location (Fig 3A and B and Fig S1B). Tested individually at physiological concentration, ascr#8 (50%) and ascr#2 (40%) gave the strongest response but all four were less active than the blend (Fig S1C). This suggested that C. elegans dauer larvae were able to perceive and respond to single components of the dispersal blend but the complete four-component blend was necessary to restore the activity.


Interspecific nematode signals regulate dispersal behavior.

Kaplan F, Alborn HT, von Reuss SH, Ajredini R, Ali JG, Akyazi F, Stelinski LL, Edison AS, Schroeder FC, Teal PE - PLoS ONE (2012)

An ascaroside blend regulates C. elegans dispersal behavior, and the dispersal blend is recognized by other nematodes.(A) Identification of the dispersal blend. Images (∼250 nematodes) are representative of 9, 10, and 11 experiments of control (0.25% E. coli (HB101)), synthetic blend with 0.25% E. coli (HB101) and dauer supernatant, respectively. (B) Quantification using Image J (http://rsbweb.nih.gov/ij/download.html). Control vs synthetic blend student's t-test unpaired (p<0.02). (C) S. feltiae IJs (∼250) response to the dispersal blend; four experiments for each treatment. (D) Response of root-knot J2s (Meloidogyne spp., mixture of M. incognita, M. javanica, and M. floridensis) to the C. elegans dispersal blend. The data represent 19 and 20 experiments from control water and C. elegans dispersal blend, respectively. At 2 h, using a student's t-test, unpaired, p<0.007.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3368880&req=5

pone-0038735-g003: An ascaroside blend regulates C. elegans dispersal behavior, and the dispersal blend is recognized by other nematodes.(A) Identification of the dispersal blend. Images (∼250 nematodes) are representative of 9, 10, and 11 experiments of control (0.25% E. coli (HB101)), synthetic blend with 0.25% E. coli (HB101) and dauer supernatant, respectively. (B) Quantification using Image J (http://rsbweb.nih.gov/ij/download.html). Control vs synthetic blend student's t-test unpaired (p<0.02). (C) S. feltiae IJs (∼250) response to the dispersal blend; four experiments for each treatment. (D) Response of root-knot J2s (Meloidogyne spp., mixture of M. incognita, M. javanica, and M. floridensis) to the C. elegans dispersal blend. The data represent 19 and 20 experiments from control water and C. elegans dispersal blend, respectively. At 2 h, using a student's t-test, unpaired, p<0.007.
Mentions: Next we investigated whether this bioassay could also be used to test for dispersal of C. elegans dauer larvae. For this assay, we used a growth medium from a developmentally synchronized C. elegans liquid culture that had produced 60% dauer larvae [19]. Following removal of all nematodes, this dauer inducing medium containing L1 and L2D secretions strongly induced dispersal behavior in the C. elegans dauer. Using LC-MS, the dauer forming medium was analyzed for the known ascarosides (ascr#1, ascr#2, ascr#3, ascr#4, ascr#5, ascr#6, ascr#7, ascr#8, and icas#9) and was found to contain four known ascarosides (ascr#2, ascr#3, ascr#8, and icas#9) [10], [14], [15] (Fig 2 and Fig S1A), all previously shown to individually promote dauer entry in C. elegans[10], [13], [14]. The concentrations of the ascarosides in the dauer forming culture medium were estimated as: ascr#2 (3.68 pmol/µl), ascr#3 (0.165 pmol/µl), ascr#8 (0.25 pmol/µl) and icas#9 (0.005 pmol/µl). A synthetic blend of these ascarosides was then tested for dispersal activity, using the dauer conditioned medium as a positive control. The media was estimated to contain approximately half of the original 0.5% E. coli (HB101) food source, thus 0.25% E. coli was added to the synthetic test samples, as well as to a water control to prevent food searching behavior induced by the absence of food. The number of dispersing nematodes was normalized to the percent of the positive control response. In the presence of just the food (negative control), approximately 35% of the dauer larvae left the release location. However, with the addition of the synthetic ascaroside blend, nearly twice as many nematodes (62%) moved away from the release location (Fig 3A and B and Fig S1B). Tested individually at physiological concentration, ascr#8 (50%) and ascr#2 (40%) gave the strongest response but all four were less active than the blend (Fig S1C). This suggested that C. elegans dauer larvae were able to perceive and respond to single components of the dispersal blend but the complete four-component blend was necessary to restore the activity.

Bottom Line: Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends.Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

View Article: PubMed Central - PubMed

Affiliation: Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Gainesville, Florida, United States of America. fkaplan@ufl.edu

ABSTRACT

Background: Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.

Methodology/principal findings: Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.

Conclusions/significance: Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

Show MeSH
Related in: MedlinePlus